Moved private receipt storage from wp-content root into wp-content/uploads/ainbae-receipt-upload-for-woocommerce/ using wp_upload_dir() per WordPress guidelines
Replaced WP_CONTENT_DIR constant with wp_upload_dir() for correct path resolution across all WordPress configurations
Replaced echo of binary file contents with readfile() to stream files without buffering or escaping concerns
Removed broken donate link from readme.txt
Updated readme FAQ to reflect new storage path and Nginx configuration instructions